Questions are being raised about whether Pope Benedict was personally involved in covering up a case of child sex abuse by a Roman Catholic priest.
Documents seen by the New York Times newspaper suggest that in the 1990s, long before he became Pope, he failed to respond to letters about a US case.
Fr Lawrence Murphy, of Wisconsin, was accused of abusing up to 200 deaf boys.
Defending itself, the Vatican said US civil authorities had investigated and dropped the case.
For more than 20 years before he was made Pope, Joseph Ratzinger led the Congregation for the Doctrine of Faith - the Vatican office with responsibility, among other issues, for the Church's response to child abuse cases.
Allegations that the Church sought to cover up child abuse by Catholic priests in Europe have haunted the Vatican for months.
'So friendly'
The documents seen by the New York Times suggest that in 1996, the then Cardinal Ratzinger twice failed to respond to letters sent to him personally.
 |  Instead of removing [Fr Murphy] from the priesthood, they just gave him a free pass  Jeff Anderson US lawyer |
They concerned the Rev Lawrence Murphy, who worked at a Wisconsin school for deaf children from the 1950s.
Three archbishops of Wisconsin were told Fr Murphy was sexually abusing boys but those allegations were not reported to civil authorities at the time.
Alleged victims quoted by the New York Times gave accounts of the priest pulling down their trousers and touching them in his office, his car, his mother's country house, on class excursions and fund-raising trips, and in their dormitory beds at night.
"If he was a real mean guy, I would have stayed away," said Arthur Budzinski, 61, a former pupil of at St John's School for the Deaf, in St Francis, in the Diocese of Milwaukee.
"But he was so friendly, and so nice and understanding. I knew he was wrong, but I couldn't really believe it."
According to the New York Times, Fr Murphy was quietly moved to the Diocese of Superior in northern Wisconsin in 1974, where he spent his last 24 years working freely with children in parishes and schools. He died in 1998, still a priest.
Two lawyers have filed lawsuits on behalf of five men alleging the Archdiocese of Milwaukee did not take sufficient action against the priest.
One of the lawyers, Jeff Anderson, told the Associated Press news agency that the documents they had obtained on Fr Murphy, and shown to the New York Times, showed the Vatican was more concerned about possible publicity than about the abuse allegations.
"Instead of removing him from the priesthood, they just gave him a free pass," he said.
'Tragic case'
The Pope's official spokesman, Federico Lombardi, called it a "tragic case" but pointed out that the Vatican had become involved only in 1996, after US civil authorities had dropped the case.
"During the mid-1970s, some of Fr Murphy's victims reported his abuse to civil authorities," the Rev Lombardi said in a statement.
"The Congregation for the Doctrine of Faith was not informed of the matter until some 20 years later."
The Milwaukee diocese was asked to take action by "restricting Father Murphy's public ministry and requiring that Father Murphy accept full responsibility for the gravity of his acts", the Rev Lombardi added.
He also said that Fr Murphy's poor health and a lack of more recent allegations had been factors in the decision not to defrock him.
But the Vatican's decision not to carry out its own investigation is the question that brings the now Pope's own involvement centre stage, says BBC religious affairs correspondent Christopher Landau.
Victims of sexual abuse by priests have long argued that the Church has been more interested in protecting its reputation and helping its priests than seeking justice for victims, our correspondent adds.
Fr Murphy died in 1998, with - in the Church's view - no official blemish on his priestly record.
But questions about why Cardinal Ratzinger failed to respond to concerns being raised by American archbishops still demand answers, our correspondent says.
And such questions mean that this sexual abuse crisis continues to have an impact at the very highest level in the Roman Catholic church, he adds.
Thankyou BBC
